Sir J. W. Daivson — On Dendrerpeton Acadianum, etc. 149 



stowing portions of four of the bones in position, and giving for 

 one of the toes of the fore-foot a length of about 2-3 centimetres; 

 also a few of the anterior abdominal scutes. All the bones repre- 

 sented belong to the anterior parts of the animal ; the portioia 

 of the tree containing its posterior parts had unfortunately been 

 destroyed or removed by the sea. 



I have remarked in previous memoirs that possibly the animals 

 found in the erect trees, while they must all have been of terrestrial 

 rather than aquatic habits, may in some cases have been young 

 individuals of the species to which they belonged. This supposition 

 is to a certain extent borne out by the present specimens, which 

 are considerably larger than the corresponding parts of individuals 

 previously found, and have the bones more ossified and more 

 strongly sculptured. Possibly, however, we may not yet know the 

 species in its full magnitude. 



This suggests the question whether D. Oweni may be founded on 

 still younger individuals of the same species. The likelihood of this 

 is not, however, increased by the new discoveries. The specimen 

 of D. Oioeni found in the tree of 1890 is quite as distinct as those 

 previously found. It has longer, more curved and pointed teeth, 

 thinner and less sculptured cranial bones. The mandibles are only 

 very feebly sculptured. The limbs and feet seem to have been similar 

 to those of D. Acadianum, but the abdominal bony scales were 

 narrower and more pointed or "oat-shaped," and the skin of the 

 upper surface more distinctly scaly. On the whole, therefore, the 

 evidence is in favour of D. Oweni having been a smaller species 

 allied to, but presenting so far as known no connecting links with, 

 its larger congener. 



HylonoviUs Lyelli, Dawson, Journ. Geol. Soc, Lond. vol. xv. 1859, 



p. 274. 



Though the newly-found specimens throw no farther light on the 

 amphibians of the group Microsauria found in the same repositories 

 with Dendrerpeton, they have invited comparison and fresh study of 

 the material previously obtained, and 1 desire in this connexion to 

 state the reasons which have induced me from the first to maintain 

 that Hyhnomus, Hylerpeton,^ Smilerpeton, and Fritschia - are not 

 Labyrinthodonts properly so called, and belong to a quite distinct 

 group, making in some respects nearer approach to the reptilian 

 order to which the Proterosaurus of the Permian belongs. 



We may take Hylonomus Lyelli, the best known of these animals, 

 as a type, and I would state the following points of comparison with 

 Dendrerpeton, and most if not all other typical Labyrinthodonts. 



1. As to the skull, this is large behind and pointed in front, and 

 its bones are smooth, while the teeth are perfectly simple, without 

 any trace of fluting or plication of the enamel, and there are no 

 interior large teeth. The nasal and maxillary bones are smooth, 

 thin, and elongated. The parietal bones larger and more convex 



1 Owen, J.G.S. vol. xviii. 1862, p. 241. 



2 Dawson, Phil. Trans. Eoyal Society, 1882, pt. ii. pp. 638, 641. 



